Signaling-circuit



(NoModeL J. J, OGONNELL.

SIGNALING CIRCUIT.

Patented Mar. 3, 1896.

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UNITED STATES PATENT OFFICE.

JOSEPH J. OCONNELL, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE AMERICAN BELLTELEPHONE COMPANY, OF BOSTON, MASSACHUSETTS.

SIGNALING-CIRCUIT.

SPECIFICATION forming part of Letters Patent No. 555,707, dated March 3,1896.

Application filed December 23, 1895. Serial No. 573,083. (No model.)

To all whom it may concern.-

Be it known that I, J OSEPH J. OCONNELL, residing at Chicago, in thecounty of Cook and State of Illinois, have invented certain Improvementsin Signalin g- Circuits, of which the following is a specification.

This invention relates to signaling between the stations of an electriccircuit, and, generally stated, comprises a system in which thesignal-sending appliances at one station when actuated remain in theirworking position, effectuating the continuous giving of the sig nal atthe other station until the attendant at the said other station takesproper action in response thereto.

Though capable of a variety of applications, this invention isespecially applicable to telephonic circuits extending betweensubstations and a central'station; and when so applied it may withadvantage be embodied in the forms of apparatus more particularlydescribed hereinafter in this specification and illustrated in thedrawings accompanying the same.

As shown, the electric circuit extends between two stations, and is atone of them associated with a key or circuit-changer, which, whenoperated, disconnects the original circuit-terminals, establishes newterminal connections, introduces the call-generator into the circuit,and is automatically locked in its new and operative position; also atthe same station, with the said call-generator and an electromagnet inthe circuit thereof, wound with but few turns of coarse wire, orotherwise so constructed or adjusted in any wellknown way that it ismade irresponsive to signaling-currents of normal strength, but becomesresponsive to any material increase in the strength of the said currentsuch as might be brought about by a change in the resistance of thecircuit when caused by connectin g the low-resistence communicatinginstruments of the other station in the circuit in place of, or inparallel with, a high-resistance signal-receiving instrument. Theexcitation of the electromagnet and the consequent attraction of itsarmature releases or unlocks the signal-sending key, which thereuponautomatically resumes its non-operative position. At the other or secondstation the circuit is normally closed through a high-resistance path orbranch, but has an alterna tive normally open path or branch preferablyof low resistance and a. switch or circuit- 5 5 changer, which in oneposition maintains the continuity of the former, holding the latteropen, but when placed in a second position may reverse this arrangement,substituting the low-resistance path for the high-resist- 6o ance pathor, preferably, connecting it in parallel therewith, in either casereducing materially the total circuit resistance.

The two stations may be the central and sub stations of atelephone-circuit, the last mentioned being the sub-station. In thatevent the normally-closed branch of course contains the usualhigh-resistance polarized bell. The alternative route includes thetelephones of standard resistance, which, as well known, is much lowerthan that of such bells, and the switch is the usual automatictelephone-switch, actuated by the removal and replacement of thetelephone and operating thereupon to effectuate the necessary circuitchanges outlined above and in turn to reverse the said changes whenrequired. Thus when the key at the central station is operated and isautomatically locked the normal circuit is there changed, its two mainconductors are united to the terminals of the call-generator, and thesignal-bell at the sub-station is made to ring and continues to ring aslong as the key remains in operative position, and when thecircuit-changer at the sub-station is operated, say by taking thetelephone from its support, in response to the ring of the signalbellthe latter is shunted or replaced by the telephone-instruments, theresistance of the circuit thereby decreased and the calling- 0 currentthereby stren gthened, so that the lowresistance electromagnet at thefirst central station is made operative and withdraws the locking devicefrom the key, releasing the same, restoring the normal condition of thecircuits at said station, and causing the operation of the call-bell atthe sub-station to cease. The key is itself a signal to the person atthe first station, as when it is locked its appearance indicates thatthe call-current Ice is on the circuit, and when it is automaticallyreset it serves to indicate that the person at the second station hasnoticed the call-signal and has operated the circuit-changer there.

I provide means whereby the person at the first station maymechanicallyunlock the key if for any reason it becomesnecessary to do so.

My invention also relates to the construction and arrangement of acircuit-changing key, which when operated to change the circuits becomesautomatically locked and retains the circuits fixed in their changedrelation and which can be automatically released from a distance ormechanically released by its operator to restore the circuits to theirnormal condition. The said key consists of a spring-retracted rodcarrying a cam or wedge and of four fiat contact-springs and isassociated with a flat-spring armature, a low-resistance ornon-sensitive electromagnet, (the armature constituting a locking devicewith the said rod,) and a mechanical releasing device, all of which aresecured to and operate in a suitable frame or support, which may be ofinsulating material, as the several parts must be insulated from eachother.

\Vhen the key is depressed its wedge forces the spring connected to oneof the main-circuit conductors away from its normal contact into contactwith another spring which is in circuit with the helices ot' the saidelectromagnet and the source of the calling-currents in a normally-openbranch or extension circuit, while the contact-spring of the othermain-circuit conductor completes a circuit with the said branch. The keymay be released electrically from a distance or mechanically at the homestation, as will be hereinafter described.

In carrying out my invention I have for the purposes of thisspecification associated it with a telephone-circuit extending betweenthe central station and a sub-station, as fully illustrated in theaccompanying drawings.

Figure 1 is a diagram of an electric telephone signaling-circuit inwhich so much of the central-oilice apparatus is shown as is necessaryto illustrate the operation of the invention, all of the sub-stationapparatus and circuits being indicated. Figs. 2 and 3 are respectivelyside and end elevations of the call-key employed by the operator at thecentral station.

Referring to all of the figures, D represents a circuit-changin gswitchconsisting of a backing E, to the opposite ends of which are secured theblocks on and 7c of insulating material, the former by means of thescrews .9 .5- and the latter by the screws 5 The rod g extends throughboth blocks m and k, as indicated, and is provided with a button 1),which is inclosed in the recess q in the latter block, so that normallyits face is flush with the end thereof. A cam or wedge f ofnonconductingmaterial is secured to the rod g by means of the screws .9s and a collara; upon the rod afifords an abutment against which thespiral springj presses and keeps the rod with the cam and button in theoutward position shown.

a, b, c, and (l are flat contact-springs held at one end and insulatedfrom one another by the block m. The spring a is connected by wire 14with the armature-spring 7L2, which is secured in the block m, and whoseouter end its serves as the armature of the loW-resistance electromagnetu and is provided with a locking-pin h and an inclined extension 7);.

r is a spring-retracted releasing button or pin, its inner end beingreduced in diameter to receive the spiral spring 5, which pressesagainst the shoulder of the pin and the shoulder in the block 75. Theouter end of the pin is in proximity to the extension 71, and is securedby a small key, as shown. The spring 7L2 is electrically united by wire18 to the electromagnet and the latter by wire 19 to the metalconnection-rod n, from which wire 21 extends to generator J and groundor return conductor G. The free end of the spring I is curved and restsupon the face of the wedge f, its central part being normally inelectrical contact with the spring 0 and its outer end united toconductor L of the main circuit.

The springs c and (1 are insulated from each other by the mechanicalconnection-piece c and are placed in a state of tension by the superiorrigidity of the spring I), the spring c being connected by wire 16 tothe usual switchboard appliances and the spring (1 to the conductor L ofthe main circuit, and. also by a wire 17 to the said switchboardappliances.

The conductor L extends to the sub-Sta tion and continues through theprimary helix i of the induction-coil I, and, to complete the localtransmitter-circuit, by wire 10 to the telephone-transmitter T, thenceby wire 5 to the normally-open contact To complete a charging-circuitfor the transmitter-battery from the central station it continues by abranch wire 8 from a point 9 on the conduct-or L through the battery 13to the hook switch it, and from thence normally by contact 2 and wire 1.to ground G. The conductor L extends to the secondary helix i of theinduction-coil land by wire 7, telephonereceiver tand wire 6 to thenormally-open contact 4 to form the main-line talking-circuit and thelow-resistance parallel path through the station on the operation ofswitch it.

A high-resistance bell C is permanently included in the bridgeornormally-closed path 20 between the conductors L and L at the points12 and 13 and forms the normal or high-resistance path through thestation.

It will be seen that normally there is a circuit from ground G,contact-point 2, hookswitch h, wire 8, conductor L, springs Z) and c towire 16, and a second circuit for signaling over the same path,supplemented, however, by a return route leading through wire 17,conductor L wire 11, and signal-bell. (1.

To operate the signal at the central-oiilee switchboard, the telephone15 is removed from the hook-switch, which, rising, impelled by thespring S takes off the ground G and closes the main-conductor circuitsjust described through the telephone branch extending from theswitch-contact 4: to the point 13 on conductor L and containing thereceiver and induction coil, all in a manner well understood and formingno part of this invention.

In the operation of the invention, when the central-station operatorwishes to signal the sub-station the button 19 is pressed inward untilit strikes the bottom of the recess q. The plate to upon the under sideof the wedge f has then passed from the pin it and the resiliency of thespring It has brought the pin upward so that it has engaged the end ofthe plate w and locked the rod 9 and wedge f in the depressed oroperative position. The wedge f forces the spring I) upward, separatingit from the spring 0 and pressing it into contact with spring Ct. Thesprings c and (1 follow the rising of the spring I) by reason of theirresiliency until the end of the spring (1 comes to rest under thecontact 0.

The-changes effected in the circuits will be seen by tracing from groundG wire 21, and generator J, plate n, wire 19, electromagnet u, wire 18,spring 7L2, wire let, springs to and b, conductor L to point 12, wire20, and bell 0, point 13, conductor L spring (1, contact 0, wire 15 toground G and the current from the generator J passing over this circuitcauses the bell O to ring, which ringing continues until the circuit isagain changed. When the telephone 2, is removed from its support inanswer to the call, a low-resistance parallel circuit is established bythe switch It round the high-resistance bell O, which is therebyshunted, and as the resistance of its helices is removed from the directcircuit, or are to be considered jointly with that of the telephones,the current from the generator J is thereby strengthened, so that itsufficiently excites the electromagnet u, and its armature 77 isattracted, releasing the pin 72. from the plate w and permitting thespiral spring j to force the rod g with its wedge f away from the spring1), whose resiliency restores,

the circuits to their normal condition. The circuit formed by theremoval of the telephone from its support may be traced from generatorJ, wires 21 and 19, electromagnet to, wire 18, spring 71?, wire 14,springs co and b, conductor .L to point 9, wire 8, and battery 13,switch 72., contact 4, wire 6, telephone 15, wire 7, secondary helix 2,wire 11, conductor L spring d, contact 0, and from ground G2 to ground GThe return-wire 50 may be substituted for the grounds in a manner wellunderstood. If there is no response from the sub-station, the operatormay restore the circuit and-cut off the generator therefrom by pressingthe stud 0", whose inner end .2 presses against the inclined extension13 and forces the armature and its pin 14: away from the plate w,whereupon the spring j operates in the manner previously described. Thebutton p serves as a signal to the operator to indicate whether thecurrent from the generator is flowing on the line or not, for if it isthe button is depressed, and if not it is flush with the face of theblock 70.

Having now fully described my invention, I claim- 1. In an electriccircuit, the combination of a high-resistance signaling-instrumentconnected therewith; a signal-current generator; a key orcircuit-changer controlling the said generator and adapted to connect itwith the said circuit; an automatic locking device for the said keyadapted to hold the same in operative position; means for strengtheningthe said signaling-current after the signal has been received,consisting of a normally-open branch circuit of relatively lowresistance associated in parallel with the said signalinginstrument, anda switch for closing the same, to reduce the circuit resistance; and areleasing-electromagnet associatedwith the said key and adapted tounlock the same, the said magnet being irresponsive to the normalsignaling-current, but responsive to the same when strengthened by theclosure of the lowresistance branch, substantially as described.

2. An electric circuit connecting two stations, provided at the firststation with a circuit-changing and self-locking call-key,alowresistance, key-releasing electromagnet, and a generator ofcall-currents; and at the second station with a high-resistancecall-receiving apparatus in a bridge between the conductors of thecircuit, and a relatively low resistance-communicating apparatus in anormally-open branch parallel with the said callreceiving apparatusbetween the said conductors, whereby the key having been locked asdescribed may be released automatically, upon the closure of thenormally-open parallel circuit shunting the call-receiving apparatus,and the consequent strengthening of the call-currents substantially asdescribed.

3. In a telephone-circuit connecting a central station with asub-station, the combination of a circuit-changing and self-lockingcall-key; a generator of signaling-currents; and a low-resistance,lock-controlling electromagnet in the circuit of said generator placedat the former station; with a high-resistance call-bell connectedbetween the main circuit conductors; a normally-open branch circuitcontaining the station-telephones, in parallel with the said bellbranch, and of relatively low resistance; and an automatictelephonesupporting switch controlling the said open branch, and adaptedon the removal of the telephone from its support, to close the same, atthe latter station, whereby the call-current is sent to line and the keylocked on the operation of the said key at one station, and whereby thesaid electromagnet is excited and the key released, when the telephoneis taken from its support at the other station, substantially as and forthe purpose specified.

4. The combination of a telephone-circuit extending between twostations; a closed callbell branch, and a normally-open telephone branchconstituting paths of high and low resistance respectively between themain-circuit conductors; an d a switch holding the lowresistance branchclosed or open according to its position, at one of the said stations 3and a call-generator; a key controlling the same, and when operatedadapted to connect it with the circuit; a lock or detent adapted to holdthe said key in operation; and a releasingelcctromagnet interposed inthe generatorcircuit at the other of said stations; the said magnetbeing wound or adjusted to be irresponsive to the current of thegenerator when the switch at the first station is in its highresistanceposition, but to become responsive thereto, release the key, anddisconnect the generator, when strengthened by the transfer of the saidswitch to its low-resistance position.

5. The combination of an electric circuit; and a key which whenmanipulated disconnects the normal terminal connections of theeircuit-conductors, and connects one of the said conductors with one endof a call branch, including an electric generator and an electromagnet,and at the same time connects the other side or conductor of the circuitwith the opposite end of the said call branch; means for locking thekey; and means for both antomatically and manually releasing the same.

(5. The combination of an electric circuit with a key which whenmanipulated disconnects the normal terminal devices of thecircuit-conductors and connects one of the said conductors with agrounded call branch, including an electric generator, and anelectromagnet; and at the same time connects the other side or conductorof the circuit with the ground; means for automatically locking the keywhen it is manipulated; means for automatically releasing it from adistance; and means associated with the said key, also for manuallyreleasing the same.

In testimony whereof I have signed my name to this specification, in thepresence of two subscribing witnesses, this 10th day of December, 1895.

JOSEPH J. OOONNELL.

Vitnesses:

GRENVILLE II. HOWARD, ANNA B. RAYMOND.

